pub fn dp_rec_mc(mut amount: u32) -> u32 {
    let deno = [100, 50, 30, 20, 10, 5, 2, 1];
    let mut cnt = 0;
    while amount > 0 {
        for item in deno {
            if amount >= item {
                amount -= item;
                cnt += 1;
                break;
            }
        }
    }
    cnt
}
